This invention relates to communications systems and specifically to a virtual channel communications system.
Communications systems frequently require operation over several bands using several different waveforms. These communications systems require varying levels of connectivity and frequently operate simultaneously in receive and transmit modes on several bands. In the past a dedicated channel for each band was implemented on various types of platforms. On a typical airborne platform such as the US Navy E-2C seven or more channels would be implemented with associated transceivers, power amplifiers, and antennas. These multiple channels add to the amount of equipment required with increased weigh and cost with reduced reliability.
Using seven dedicated power amplifiers in an airborne platform such as the E-2C is at a very severe weight penalty when duty cycle numbers indicate that only four amplifiers are needed to provide the required communications connectivity. The use of four power amplifiers with a 100% duty cycle each to service seven waveforms has in past architectures required extensive RF switching. An RF switch matrix is used to route the RF signal from transceivers or antennas to the four power amplifiers. This approach, while providing better capability than traditional non-switched architectures, still has many drawbacks. The RF switch matrix is very complex, large, heavy and also quite expensive. In addition, performance also suffers because of isolation and insertion loss issues inherent in RF switch architectures.
What is needed is a system architecture that provides the required communications connectivity while reducing equipment quantity and weight. Furthermore such a system requires equipment with new capabilities such as a power amplifier that is able to support the varying system channel requirements while offering reduced weight and cost.